The present invention relates to 2-chloroethyl phosphonate mixtures, a process for the preparation thereof and flame retardant compositions comprising organic polymers together with said 2-chloroethyl phosphonate mixtures.
Certain phosphorus esters such as phosphate esters have been employed heretofore as flame retardant additives but have suffered from the defect of low-molecular weight and loss by volatilization from the substrate polymeric materials in which the phosphates were employed. For example, the addition of such phosphates to a polyurethane foam resulted in loss of some of the phosphates when the foams were heat aged, with consequent reduction of fire-retardancy.
In other cases, the flame retardant additives do not lend themselves well to certain desired formulation characteristics in production of rigid polyurethane foams such as cream time, string time, rise time and tack-free time. Cream time is the time interval between (a) the start of the final mixing in laboratory or batch type mixing or the time the material is first poured in machine mixing and (b) the point at which the clear mixture turns creamy or cloudy and starts to expand. String time is the time between pouring the mixed liquids into the container and the time that long strings of tacky material can be pulled away from the surface of the foam when the surface is touched with a wooden spatula or with the fingers. Rise time is the time interval between the liquid mixture being poured into the mold and the completion of expansion of the foaming mass. Tack-free time is the time between pouring the liquid mixture and the time that the surface of the foam can be touched with a spatula or a finger without sticking. The aforesaid definitions are taken from "A Glossary of Urethane Industry Terms" by S. Alan Stewart, The Martin Sweets Company, Inc., 1971.